The above-described cutting inserts are used for milling outside surfaces and forming undercuts on crankshafts. Such an application is described by way of example in U.S. Pat. No. 6,374,472 in a disk-shaped outside miller that is driven such that the chip-removing machining takes place at cutting speeds above 160 m/min. To this end both the crankshaft and the outside miller are rotated. To machine the cylindrical surfaces of the rotating workpiece, with a crankshaft machining its journals, tangentially attached cutting inserts are used that have according to the teachings of U.S. Pat. No. 6,374,472 generally rectangular upper faces that are defined by peripheral main cutting edges. Immediately adjacent there are four side faces that together form auxiliary cutting edges. The upper face has near each corner formed by adjacent main cutting edges a flat or recess that extends up to the two adjacent cutting edges and when the cutting insert is installed tangentially defines between the effective cutting face that is formed by the side faces and the effective free face that is formed by the upper rectangular surface an angle of 75° to 85° so that there is an effective cutting angle between −5° and +15°. In order to machine the crankshaft in any case two different cutting inserts are required, one of which is mounted radially for making the undercut and the other tangentially for finishing the journal.
Tools are also known from the prior art that are rotated in so-called single or double rotary systems. With single rotary systems a tool is moved radially to the rotating tool. With double-rotary systems a row of cutting inserts on the periphery of a disk-shaped tool support are set in steps along a first section of the disk. This tool is swung along an arc radially to the rotating workpiece as described in principal in U.S. Pat. Nos. 4,790,698 and 5,037,248 and EP 0,286,771. Even with these bar-shaped or disk-shaped tools two geometrically different types of cutting inserts are used for machining the journals and making the undercuts.
It is also known that for precisely maintaining the desired tolerances in the crankshaft or other rotating workpiece being machine to use shims when installing the cutting inserts to set the cutting width and to use hardened support pieces to prevent imbedding in the seat of the cutting insert. Cutting inserts, support pieces, and shims can be set in cassettes that are secured to the disk- or bar-shaped tool support.
The milling tool works more cost efficiently with a shallower cut, that is with the gentlest possible machining operation. This can also be achieved when the tool has the maximum possible number of effective cutting edges. Thus according to U.S. Pat. No. 6,805,520 a disk miller is provided with tangentially clamped cutting inserts at an axial inclination of 15° to 35°, preferably 20° to 30°. The furthest back cutting corners of the tangentially clamped cutting inserts lie relative to the milling direction on a straight line perpendicular to the rotation direction of the disk miller that has from the frontmost cutting edge of the following radially clamped cutting insert a spacing of ≦5 mm, preferably ≦2 mm, down to negative values. By the use of so-called indexable cutting plates that have several usable cutting edges, the costs for the cutting inserts can be substantially reduced; thus the above-described radially or tangentially clamped cutting inserts each have four usable cutting edges. If the usable cutting edges of the cutting inserts are all worn, the cutting inserts have to be replaced, which requires that the required cutting-insert types be stocked.